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Liver Tumors

Overview

Angiogram of the liver prior to chemoembolization demonstrates large tumor vessels.

Liver cancer is one of the most common malignant tumors, affecting thousands of people every year. Tumors can either start in the liver (hepatocellular carcinoma or hepatoma) or travel to the liver from other organs. The most common origins of these tumors are the gastrointestinal tract (colon or stomach), pancreas, lung, breast, skin, and kidney.

A liver tumor that originates from another part of the body is called a metastasis. There are many imaging studies that can identify metastases including ultrasound, CAT scan, MRI and PET scan.

The most common malignant tumor that originates in the liver is called hepatoma or hepatocellular carcinoma. Usually, this presents as a single tumor but multiple tumors are not uncommon. Risk factors for hepatoma include cirrhosis of the liver and hepatitis B. The incidence of hepatoma in the United States is rising due to the increased incidence of hepatitis B infection.

Often it is difficult to differentiate a hepatoma from a metastasis on imaging studies. It is usually necessary to perform a procedure called a biopsy to help distinguish between these two diseases before a patient starts treatment for a liver tumor. The biopsy is often done using a CAT scan or ultrasound study to help guide the needle directly into the tumor.

Treatments

CAT scan after chemoembolization, showing treated tumor. The tumor appears bright white as it has been replaced by the chemoembolization agent.

Once the patient's tumor type has been identified, the best treatment option can be determined. Treatment options include surgery, chemotherapy, chemoembolization, and radiofrequency ablation.

Surgery

Currently, the best therapy for a liver tumor patient is surgical resection, or removal of the tumor. Unfortunately, only about 20% of patients are candidates for surgery. Patients may be ineligible for surgery due to decreased liver function, the presence of one or more tumors outside the liver, and tumors that are scattered throughout the liver. Surgical removal does not ensure long-term survival, however, because even if the tumor is completely removed, new tumors may arise in other areas of the liver. A surgical oncologist is the most qualified physician to determine if a liver tumor is resectable.

Chemotherapy

A needle is placed through the skin directly into the liver tumor, and a bouquet of very thin electrodes is then extended from the end of the needle into different portions of the tumor. This will allow heating of the entire tumor. Image courtesy of RITA Medical

Chemotherapy entails giving drugs through an intravenous catheter. The drugs then course through the blood stream and distribute themselves throughout the body. The drugs kill tumor cells by different mechanisms including disruption of cellular growth and actual tumor cell destruction. Chemotherapy is currently used to treat liver metastases. However, there is currently no chemotherapeutic agent that is effective against hepatocellular carcinoma.

Regional Therapies

Regional therapies are those that target the diseased part of the liver and spare other organ systems. The two most common types of these therapies are liver chemoembolization and radiofrequency ablation.

Chemoembolization

By the end of the ablation procedure the tumor has been heated to a temperature sufficient to cause death of the tumor cells. Image courtesy of RITA Medical

Interventional radiologists perform chemoembolization. Patients will first undergo pre-procedural evaluation including blood tests and a CAT scan or MRI to determine if they are potential candidates. Patients are not candidates for this procedure if the tumor occupies too much of the liver, if there is compromise of liver function, or if there is a significant amount of tumor outside of the liver.

The procedure requires hospitalization for 48 hours or less. After sedation and pain medications are given, a small incision is made in the groin and a thin hollow tube called a catheter is placed into a vessel in the groin. X-ray dye is injected and an angiogram of the vessels supplying the liver is performed. The catheter is then placed into the vessel supplying blood to the liver. A mixture containing concentrated chemotherapeutic agents and oily X-ray dye is then injected into the liver artery. The oily X-ray dye is very thick, thereby causing a blockage within the vessels that feed the tumor. The blockage within the tumor vessels allows the chemotherapeutic agents to stay within the tumor longer and enhances the overall chemotherapeutic effect. The blockage also has the added benefit of decreasing the blood supply to the tumor, which enhances tumor destruction.

Only half of the liver is treated at one time to preserve the function of the liver. If additional treatments are necessary, they are typically performed approximately 4 to 6 weeks later. Some patients need only one chemoembolization treatment if their tumor is confined to a single location in the liver. After the procedure, patients may experience some pain and fever. This is called post-embolization syndrome. These symptoms are caused by the death of the tumor cells and they are readily treated with oral medications.

Current studies demonstrate a statistically significant improvement in survival for hepatoma patients who received chemoembolization. While the data for liver metastases is very encouraging, conclusive data is not presently available.

Radiofrequency Ablation

Radiofrequency ablation (RFA) is one of the newer methods used in the treatment of liver tumors. To perform this procedure, a "multi-probed" needle is placed directly into the liver tumor. Radiofrequency energy is then applied to the needle probes by a generator. This energy leads to intense heating of the tumor cells that ultimately leads to the destruction of the tumor. Radiofrequency ablation can be performed either directly through the skin or, in difficult to reach tumors, through an incision made by a surgeon.

The temperatures generated by the probe approach 220ºF, ensuring the total destruction of the tumor. Following the procedure, patients may experience some of the symptoms of post-embolization syndrome, which are readily treated with oral medications. Patients typically are discharged the morning after the procedure.

Patients are candidates for radiofrequency ablation if they have fewer than five tumors, have tumors less than 5 cm in size, and have limited tumor outside the liver. Tumors larger than 5 cm might benefit from a combination of chemoembolization and radiofrequency ablation.